Temperament Affected Visuospatial Orienting on Discrimination Tasks.

In the Posner cueing paradigm, the early attentional capture and subsequent inhibition of return (IOR) of attention to the same location, although they are microscale phenomena measured in milliseconds, seem to encapsulate the interaction between two fundamental dimensions of behavior - engaging in and sustaining activity versus withdrawing from and inhibiting activity. In the field of differential psychology, the dynamics of reciprocal relations between these behavioral dimensions have been thought to be determined by central nervous system properties that constitute an individual's temperament. Yet the research on any differential effects of temperament on visuospatial orienting is rather sparse and has produced ambiguous results. Here, we used saccadic responses to measure whether individual differences in reactivity as a temperamental trait might affect orienting of visuospatial attention on discrimination cueing tasks. Our results suggested that, in individuals with lower reactivity, attentional capture took place at a short stimulus onset asynchrony (SOA), producing a facilitatory cueing effect, which was not the case in those who were higher in reactivity. We explain and discuss these results with the Regulative Theory of Temperament.

Does temperament have a differential effect on Inhibition of Return (IOR)?

Reaction times to targets presented at previously stimulated locations are longer after some time (approx. 300 ms) than to targets presented in new locations. This effect is widely known as Inhibition of Return (IOR). It is typically explained in terms of an inhibitory bias against returning attention to places previously attended to and thus promoting attentional activity elsewhere. Regardless of its attentional character, IOR seems to encapsulate the interaction between two fundamental dimensions of temperament: engaging in versus inhibition and withdrawal from activity. Approaching IOR in this perspective, the question has arisen as to whether individual differences in reactivity as a temperamental trait express themselves in the time course and magnitude of this effect. 90 subjects (30 low, 30 medium and 30 highly reactive individuals) participated in the study. To the best of our knowledge, there are no other studies of individual differences in these parameters of IOR that use saccadic responses to measure its effect on behavior. The results show that in individuals who are higher in terms of their reactivity, IOR starts earlier and continues at the following SOAs but its magnitude is smaller than in less reactive individuals. The results are explained and discussed in light of the Regulative Theory of Temperament. This is the final version of the Abstract which has been accepted in the revised manuscript.

Objective and Subjective Evaluation of Saccadic Eye Movements in Healthy Children and Children with Neurodevelopmental Disorders: A Pilot Study.

The objective of this study was to characterize saccades in children with neurodevelopmental disorders (NDDG, 17 children, age: 7-12 years) and compare them with a control group (CG, 15 children, age: 7-12 years), comparing the outcomes obtained with a subjective score system (Northeastern State University College of Optometry's Oculomotor test, NSUCO) with the objective analysis obtained through a commercially available Eye Tracker (Tobii Eye X, Tobii, Stockholm, Sweden) and a specialized software analysis (Thomson Software Solutions, Welham Green, UK). Children from the NDDG obtained significantly lower NSUCO scores (p < 0.001) compared with CG. Concerning eye tracking analyses, we found a significantly higher number of hypometric saccades in NDGG (p ≤ 0.044). Likewise, we found a significantly higher percentage of regressions in the NDDG for a time interval of presentation of stimuli of 1 s (p = 0.012). Significant correlations were found between different NSUCO scores and percentage of regressions, number of saccades completed and number of hypometric saccades. The presence of hypometric saccades and regressions seems to be a differential characteristic sign of children with neurodevelopmental disorders that can be detected using an objective eye tracking analysis, but also using the subjective test NSUCO that can be easily implemented in all clinical settings.

Flow dynamics of vitreous humour during saccadic eye movements.

In this work, we reveal the flow dynamics of Vitreous Humour (VH) gel and liquid phases during saccadic movements of the eye, considering the biofluids viscoelastic character as well as realistic eye chamber geometry and taking into account the saccade profile. We quantify the differences in the flow dynamics of VH gel and liquid phases using viscoelastic rheological models that are able to model the VH shear rheology, considering different amplitudes of saccadic movements (10∘, 20∘, 30∘ and 40∘). For this purpose, the computational fluid dynamics (CFD) open source software OpenFOAM® was used. The results portray a distinct flow behaviour for the VH gel and liquid phases, with inertial effects being more significant for the VH liquid phase. Moreover, the Wall Shear Stress (WSS) values produced by the VH gel phase are more than twice of those generated by the VH liquid phase. Results also show that for different amplitudes of eye movement both the velocity magnitude in the vitreous cavity and the shear stresses on the cavity walls rise with increasing saccadic movement displacement.

Video-oculography eye tracking towards clinical applications: A review.

Most neurological diseases are usually accompanied by a broad spectrum of oculomotor alterations. Being able to record and analyze these different types of eye movements would be a valuable tool to understand the functional integrity of brain structures. Nowadays, video-oculography is the most widely used eye-movements assessing method. This paper presents a study of the existing eye tracking video-oculography techniques and also analyzes the importance of measuring slight head movements for diseases diagnosis. In particular, two types of methods are reviewed and compared, including appearance-based and feature-based methods which are further subdivided into 2D-mapping and 3D model-based approaches. In order to demonstrate the advantages and disadvantages of these different eye tracking methods for disease diagnosis, a series of comparisons are conducted between them, addressing the complexity of the system, the accuracy achieved, the ability to measure head movements and the external conditions for which they have been designed. Lastly, it also highlights the open challenges in this research field and discusses possible future directions.

Attenuation of visual evoked responses to hand and saccade-initiated flashes.

Sensory attenuation refers to reduced brain responses to self-initiated sensations relative to those produced by the external world. It is a low-level process that may be linked to higher-level cognitive tasks such as reality monitoring. The phenomenon is often explained by prediction error mechanisms of universal applicability to sensory modality; however, it is most widely reported for auditory stimuli resulting from self-initiated hand movements. The present series of event-related potential (ERP) experiments explored the generalizability of sensory attenuation to the visual domain by exposing participants to flashes initiated by either their own button press or volitional saccade and comparing these conditions to identical, computer-initiated stimuli. The key results showed that the largest reduction of anterior visual N1 amplitude occurred for saccade-initiated flashes, while button press-initiated flashes evoked an intermediary response between the saccade-initiated and externally initiated conditions. This indicates that sensory attenuation occurs for visual stimuli and suggests that the degree of electrophysiological attenuation may relate to the causal likelihood of pairings between the type of motor action and the modality of its sensory response.

Long-Term Effects of Frontalis Fascial Slings on the Elastic Properties of the Upper Eyelid.

PURPOSE: To measure the long-term effects of frontalis slings with fascial tissues on the downward eyelid saccadic movements Methods: Downward lid saccades for 10, 20, 30, 40, and 50 degrees of downgaze were measured in a sample of 19 patients with congenital ptosis who underwent frontalis slings with fascia lata (autogenous and banked) and temporalis fascia. Mean postoperative time was 10.7 years ± 3.8 SD. Seventeen age-matched normal subjects comprised the control group. Lid movements as well as the magnitude of brow motion were quantified in all participants with an opto-electronic device that automatically corrected any head movement. RESULTS: Most patients (77.4%) displayed lagophthalmos on eyelid closure. The lid saccades of the patients were severely restricted and did not increase beyond 30 degrees of downgaze. The maximum velocity of lid saccades was also abnormally low. Although the pre- and postoperative lid positions did not differ between eyes operated with the three types of slings, interocular analysis of patients who had bilateral surgery showed that the restrictive effect on the saccadic movements was more asymmetrical with banked fascia than with autogenous tissue. Overall, there was a significant negative correlation between the surgical effect with frontalis contraction and maximum saccadic amplitude. While in controls brow motion accounted for about 3.3-9.3% of the lid saccades, it was responsible for more than 43.5-57.4% lid movements in the patients. CONCLUSION: Fascial slings have a permanent restrictive effect on the elastic properties of the lids. Postoperative lagophthalmos is a natural consequence of any type of fascial sling. Downward saccadic amplitude is negatively correlated with the surgical effect with frontalis contraction.

Influencia de los movimientos sacádicos en el rendimiento académico de estudiantes de básica primaria en situación de vulnerabilidad en la ciudad de Cúcuta / Influence of saccadic movements on elementary students'academic achievement in vulnerable situation from Cucuta (Colombia)

Resumen Objetivo: Determinar si los movimientos sacádicos influyen en el rendimiento académico de estudiantes de básica primaria. Metodología: Se tomó una muestra no probabilística por conveniencia de 121 estudiantes de básica primaria con situación de vulnerabilidad en una Ins titución Educativa de la ciudad de Cúcuta, Colombia. La muestra se dividió en dos grupos: el primero, de alto rendimiento académico, conformado por 56 estudiantes, 60 % niñas y 40 % niños, con una media de 11,70 años; el segundo, de bajo rendimiento, constituido por 65 estu diantes, 40 % niñas y 60 % niños, con una media de 12,29 años. A ambos grupos se aplicó el test de King y Devick (1976) o test K-D de movimientos sacádicos. Resultados: Los resultados mostraron diferencias estadísticamente significativas entre las medias de los tiempos de lectura de cada una de las tarjetas como en la media del tiempo total de lectura de las tres tarjetas del test K-D. También se encontraron diferencias significativas en el porcentaje de estudiantes que presentan problemas en relación con los movimientos sacádicos: en el grupo con alto rendi miento el porcentaje de estudiantes con problemas relacionados con movimientos oculares en función del tiempo es mucho menor que en el grupo con bajo rendimiento académico. Conclusión: Los resultados ponen de manifiesto la importancia de trabajar los movimientos oculares sacádicos, pues parecen influir en el rendimiento académico de los estudiantes.

Abstract Objective: This paper aims to determine whether saccades influence academic performance of elementary school students. Methodology: 121 vulnerable elementary school students from an educational institution from Cucuta, Colombia were used as non-probabilistic or convenience samples. These students were divided into two groups, as follows: 56 high academic achievers students: 60 % girls and 40 % boys, with an average age of 11.70 years and 65 underperforming average students: 40 % girls and 60 % boys, with an average age of 12.29 years. King & Devick (1976), or K-D test saccades test was applied. Results: The results showed statistically significant differences between the means of reading times of each of the cards and the average total reading time of the three test cards K-D. Also significant differences in the percentage of students who had problems with saccades, showing in the group with high yield a much higher percentage of students without problems in eye movement function at the time that the group with low aca demic performance was found. Conclusion: The results highlight the importance of working eye movements as saccadic issue which seem to influence on their students academic performance.

Attenuation of auditory evoked potentials for hand and eye-initiated sounds.

Reduction of auditory event-related potentials (ERPs) to self-initiated sounds has been considered evidence for a predictive model in which copies of motor commands suppress sensory representations of incoming stimuli. However, in studies which involve arbitrary auditory stimuli evoked by sensory-unspecific motor actions, learned associations may underlie ERP differences. Here, in a new paradigm, eye motor output generated auditory sensory input, a naïve action-sensation contingency. We measured the electroencephalogram (EEG) of 40 participants exposed to pure tones, which they produced with either a button-press or volitional saccade. We found that button-press-initiated stimuli evoked reduced amplitude compared to externally initiated stimuli for both the N1 and P2 ERP components, whereas saccade-initiated stimuli evoked intermediate attenuation at N1 and no reduction at P2. These results indicate that the motor-to-sensory mapping involved in speech production may be partly generalized to other contingencies, and that learned associations also contribute to the N1 attenuation effect.

A influência da oculomotricidade e do reflexo-vestíbulo-ocular na leitura e escrita / The influence of eye movement and the vestibular-ocular reflex in reading and writing

OBJETIVO: verificar se alterações na oculomotricidade e no reflexo vestíbulo-ocular estão relacionados com a dificuldade de leitura e escrita. MÉTODOS : foram selecionados 18 sujeitos de ambos os gêneros, faixa etária entre nove e 14 anos de idade, com audição e acuidade visual estática dentro dos padrões de normalidade, sendo um grupo de 11 sujeitos com dificuldade de leitura e escrita e outro grupo controle composto por sete sujeitos sem a dificuldade. Os exames realizados foram avaliações da linguagem escrita, acuidade visual estática, acuidade visual dinâmica, audiológica e oculomotricidade. RESULTADOS : a acuidade visual estática, calibração, nistagmo espontâneo e semi - espontâneo apresentaram-se dentro da normalidade em toda população estudada. As provas de acuidade visual dinâmica e movimento sacádico apresentaram diferença estatisticamente significante (p<0,05) entre os grupos estudados, enquanto o movimento de rastreio apresentou alterações em ambos os grupos, não ocorrendo diferença estatística. CONCLUSÃO: alterações na oculomotricidade, assim como mal desempenho do reflexo vestíbulo-ocular mostrado na acuidade visual dinâmica podem estar interferindo na dificuldade do desenvolvimento da leitura e escrita. .

PURPOSE: to determine whether changes in eye movement and vestibular- ocular reflex are related to the difficulty of reading and writing. METHODS: 18 subjects of both genders, aged between nine and 14 years of age with hearing and static visual acuity within normal limits were selected: one group of 11 subjects with reading and writing and other composite control group seven subjects without difficulty. The tests included evaluations of written language, static and dynamic visual acuity, audiological and eye movements. RESULTS: static visual acuity, calibration, spontaneous and semi- spontaneous nystagmus were within the normal range throughout the study population. Proofs of dynamic visual acuity and saccades showed statistically significant difference (p < 0.05) between the groups, while the smooth-persuit eye movements showed changes in both groups, with no statistical difference. CONCLUSION: alterations in eye movement, as well as poor performance of the vestibulo-ocular reflex shown in dynamic visual acuity may be interfering with the difficulty of the development of reading and writing. .

Eye movement alterations during reading in patients with early Alzheimer disease.

PURPOSE: Eye movements follow a reproducible pattern during normal reading. Each eye movement ends up in a fixation point, which allows the brain to process the incoming information and to program the following saccade. Alzheimer disease (AD) produces eye movement abnormalities and disturbances in reading. In this work, we investigated whether eye movement alterations during reading might be already present at very early stages of the disease. METHODS: Twenty female and male adult patients with the diagnosis of probable AD and 20 age-matched individuals with no evidence of cognitive decline participated in the study. Participants were seated in front of a 20-inch LCD monitor and single sentences were presented on it. Eye movements were recorded with an eye tracker, with a sampling rate of 1000 Hz and an eye position resolution of 20 arc seconds. RESULTS: Analysis of eye movements during reading revealed that patients with early AD decreased the amount of words with only one fixation, increased their total number of first- and second-pass fixations, the amount of saccade regressions and the number of words skipped, compared with healthy individuals (controls). They also reduced the size of outgoing saccades, simultaneously increasing fixation duration. CONCLUSIONS: The present study shows that patients with mild AD evidenced marked alterations in eye movement behavior during reading, even at early stages of the disease. Hence, evaluation of eye movement behavior during reading might provide a useful tool for a more precise early diagnosis of AD and for dynamical monitoring of the pathology.

Saccades and smooth pursuit eye movements in central vertigo.

In order to analyze the diagnostic efficiency of saccadic and pursuit eye movements compared to findings from brain magnetic resonance imaging in patients with central vertigo, 108 patients were selected from 580 dizzy patients as cases of suspected central origin; the saccadic and pursuit eye movements were evaluated by electronystagmography and findings were compared to information from magnetic resonance imaging. The study of oculomotor movements in patients suspected of having a central lesion revealed a 83.3% sensitivity and 21.2% specificity. Restricting consideration to severe alterations in eye movements as indicative of a central origin, this test gives a 71.4% sensitivity and 50.0% specificity. In conclusion, the study of alterations in oculomotor movements, in patients with suspected central lesions, proved to be a test with good sensitivity also compared with results of magnetic resonance imaging.

Movimentos sacádicos durante leitura de texto em crianças e universitários bons leitores / Los movimientos sacádicos durante la lectura de textos en niños y profesores de universidad considerados buenos lectores / Saccadic movements during reading of text in children and university professors considered good readers

O presente estudo avaliou crianças de quarta série e universitários considerados bons leitores em prova computadorizada de leitura de textos. Traçados dos movimentos oculares obtidos durante a leitura possibilitam comparar os dois grupos em: número de sacadas regressivas; tipo de sacada regressiva que podia ser intra-palavra ou entre-palavra; e classificação gramatical das palavras que sofreram regressão. Resultados mostram que crianças apresentaram maior número de sacadas regressivas do que universitários. Ambos os grupos realizaram mais regressões entre-palavras para a palavra imediatamente anterior à última fixação do que regressões intra-palavra. Os dois grupos realizaram mais sacadas regressivas intra-palavras nos seguintes tipos de palavras: substantivos, adjetivos e verbos. Regressões para a palavra anterior ocorreram principalmente nos pares de palavra: conjunção-verbo; adjetivo-substantivo e preposição-substantivo. De modo geral, os bons leitores realizam menos sacadas regressivas do que crianças em processo de alfabetização, no entanto o padrão das sacadas regressivas e o tipo de palavras que sofrem regressão são parecidos nos dois grupos. Também foi observado um maior número de sacadas regressivas no início de cada linha do texto, que pode ser explicado em função do processamento parafoveal na leitura. Regressões para a palavra anterior podem estar relacionadas ao fato de que, dependendo da classe gramatical da palavra, há uma maior possibilidade dela não ser fixada.

The present study evaluated 4-grade children and university professors considered good readers in a computerized test of text reading. Trajectories of eye movements obtained during reading made possible to compare the two groups regarding the number of regressive saccades; type of regressive saccade - that could be intra-word or inter-word; and grammatical classification of words that suffered regression. Results show that children presented a higher number of regressive saccades than university professors. Both groups carried out more inter-word regressions to the word immediately antecedent to the last fixation than intra-word regressions. The two groups carried out more intra-words regressive saccades in the following word types: nouns, adjectives and verbs. Regressions to the previous word took place principally in word couples conjunction-verb, adjective-noun, and preposition-noun. On the whole, good readers carry out fewer regressive saccades than children in the process of literacy, but the standard of regressive saccades and the type of words that suffer regression are similar in the two groups. Also a higher number of regressive saccades was observed in the beginning of each line of the text, which can be explained by paraphoveal processing in reading. Regressions to the previous word may be related to the fact that, depending on the grammatical class of the word, there is a higher possibility of its not fixed.

Este estudio evaluó a niños del 4° grado y profesores de universidad considerados buenos lectores en una prueba automatizada de lectura de texto. Trayectorias de movimientos del ojo obtenidos durante la lectura han hecho posible comparar los dos grupos en cuanto al número de movimientos sacádicos regresivos; el tipo de movimiento sacádico regresivo - que podría ser intrapalabra o interpalabra; y la clasificación gramatical de palabras que sufrieron la regresión. Los resultados muestran que los niños presentaron un número más alto de movimientos sacádicos regresivo que los profesores de universidad. Ambos grupos realizaron más regresiones interpalabra al la palabra inmediatamente antecedente a la última fixación que regresiones intrapalabra. Los dos grupos realizaron más movimientos sacádicos regresivos intrapalabras en los tipos de palabra siguientes: sustantivos, adjetivos y verbos. Las regresiones a la palabra anterior ocurrieron principalmente en parejas conjunción-verbo, sustantivo-adjetivo y preposición-sustantivo. En general, los buenos lectores realizan menos movimientos sacádicos regresivos que niños em el proceso del alfabetismo, pero el estándar de movimientos regresivos y el tipo de palabras que sufren la regresión son similares en los dos grupos. También un número más alto de estos movimientos fue observado al principio de cada línea del texto, lo que se puede explicar por el procesamiento parafoveal en la lectura. Las regresiones a la palabra anterior pueden estar relacionadas con el hecho que, según la clase gramatical de la palabra, hay una posibilidad más alta de su no fijación.